Use ScopedTaskEnvironment instead of MessageLoopForUI in ash tests.

Use ScopedTaskEnvironment instead of MessageLoopForUI in ash tests.

ScopedTaskEnvironment allows usage of ThreadTaskRunnerHandle and
base/task_scheduler/post_task.h within its scope. It should be
instantiated in everytest that uses either of these APIs
(i.e. no test should instantiate a MessageLoop directly).

Motivation for ScopedTaskEnvironment can be found in:
https://docs.google.com/document/d/1QabRo8c7D9LsYY3cEcaPQbOCLo8Tu-6VLykYXyl3Pkk/edit

BUG=708584
R=gab@chromium.org
TBR=sky@chromium.org

Review-Url: https://codereview.chromium.org/2846723004
Cr-Commit-Position: refs/heads/master@{#467987}
Committed: https://chromium.googlesource.com/chromium/src/+/40b0d9cabbed3a1447f51af3ffc5a287e86f9390

[fdoray, 2017-04-27 18:27:19]

The CQ bit was checked by fdoray@chromium.org to run a CQ dry run

[fdoray, 2017-04-27 18:27:21]

gab@: PTAL

The change will then be TBRed to the owner.

[commit-bot: I haz the power, 2017-04-27 18:28:03]

Dry run: CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-27 18:55:22]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2017-04-27 18:55:24]

Dry run: This issue passed the CQ dry run.

[sky, 2017-04-27 22:14:57]

LGTM

[fdoray, 2017-04-28 13:50:52]

The CQ bit was checked by fdoray@chromium.org

[commit-bot: I haz the power, 2017-04-28 13:51:35]

CQ is trying da patch.

Follow status at:
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2017-04-28 14:12:38]

CQ is committing da patch.

Bot data: {"patchset_id": 1, "attempt_start_ts": 1493387452969750, "parent_rev":
"992dc1adae8123ed7cacdeaa7f321bbbbf7837f5", "commit_rev":
"40b0d9cabbed3a1447f51af3ffc5a287e86f9390"}

[commit-bot: I haz the power, 2017-04-28 14:12:49]

Description was changed from

==========
Use ScopedTaskEnvironment instead of MessageLoopForUI in ash tests.

ScopedTaskEnvironment allows usage of ThreadTaskRunnerHandle and
base/task_scheduler/post_task.h within its scope. It should be
instantiated in everytest that uses either of these APIs
(i.e. no test should instantiate a MessageLoop directly).

Motivation for ScopedTaskEnvironment can be found in:
https://docs.google.com/document/d/1QabRo8c7D9LsYY3cEcaPQbOCLo8Tu-6VLykYXyl3P...

BUG=708584
R=gab@chromium.org
TBR=sky@chromium.org
==========

to

==========
Use ScopedTaskEnvironment instead of MessageLoopForUI in ash tests.

ScopedTaskEnvironment allows usage of ThreadTaskRunnerHandle and
base/task_scheduler/post_task.h within its scope. It should be
instantiated in everytest that uses either of these APIs
(i.e. no test should instantiate a MessageLoop directly).

Motivation for ScopedTaskEnvironment can be found in:
https://docs.google.com/document/d/1QabRo8c7D9LsYY3cEcaPQbOCLo8Tu-6VLykYXyl3P...

BUG=708584
R=gab@chromium.org
TBR=sky@chromium.org

Review-Url: https://codereview.chromium.org/2846723004
Cr-Commit-Position: refs/heads/master@{#467987}
Committed:
https://chromium.googlesource.com/chromium/src/+/40b0d9cabbed3a1447f51af3ffc5...
==========

[commit-bot: I haz the power, 2017-04-28 14:12:50]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/chromium/src/+/40b0d9cabbed3a1447f51af3ffc5...